燃煤烟气净化设施对汞排放特性的影响

为研究燃煤锅炉烟气净化设施对汞排放特性的影响，采用Ontario-Hydro方法，对设有催化脱硝、静电除尘、海水脱硫的300 MW燃煤锅炉排放烟气中汞的含量与形态进行分析，同时测定锅炉的煤、底渣、飞灰等固体样品以及脱硫塔前后、曝气之后海水样品中的汞含量。实验结果为：烟气中的气态汞占总汞的79.1%以上，脱硝催化剂对汞的价态具有强烈的转化作用，烟气中83.4%的气态Hg0被氧化成气态Hg2+；静电除尘对颗粒态汞的去除率几乎达到100%；在脱硫塔中，海水对烟气中汞的洗脱率高达73.6%，曝气后排放前的海水中含汞量是新鲜海水的5.5倍。研究表明锅炉烟气净化设施对汞的排放特性有着重要的影响。

Effect of Flue-gas Cleaning Devices on Mercury Emission From Coal-fired Boiler

In order to study the effect of flue-gas cleaning devices on mercury emission from coal-fired boiler, Ontario-Hydro method had been applied to determine the mercury concentration and speciation in the flue-gas emitted from a 300MW coal-fired boiler, which was equipped with various pollution control devices, including selective catalyst reduction (SCR) De-NOx system, electrostatic precipitator (ESP), and flue-gas seawater De-SO2 system (FGD). Mercury concentration in raw coal, bottom ash and fly ash of the boiler, seawater at the inlet and outlet of SO2 absorption reactor and the drainage of aeration sink, were also analyzed. The results indicate that the percentage of gaseous mercury in total mercury discharged is more than 79.1%. De-NOx catalyst strongly affects the mercury speciation transformation, showing a conversion rate of 83.4% for Hg0 to Hg2+. The removal efficiency of particulate mercury by ESP is close to 100%. With seawater FGD, the removal efficiency of mercury is as high as 73.6%. The mercury concentration in the seawater of drainage from aeration sink is 5.5 times higher than that in fresh seawater. The study shows that the flue-gas cleaning devices in coal-fired power plant play an important role on mercury emission characterization.